Page 66 - Coulson Richardson's Chemical Engineering Vol.6 Chemical Engineering Design 4th Edition

FUNDAMENTALS OF MATERIAL BALANCES
H 52.26%
C 2 4
C H 55%
2 4
H OH 5.49% 49
C 2 5
Inerts 5% Reactor (C H ) O 0.16%
2 5 2
O 36.81%
H 2
O 40%
H 2
Inerts 5.28%
Note: the flow of inerts will be constant as they do not react, and it can be used to
calculate the other flows from the compositions.
Feed stream ethylene 55 mol
inerts 5 mol
water 40 mol
Product stream
52.26
ethylene D ð 5 D 49.49 mol
5.28
5.49
ethanol D ð 5 D 5.20 mol
5.28
0.16
ether D ð 5 D 0.15 mol
5.28
Amount of ethylene reacted D 55.0 49.49 D 5.51 mol
5.2 ð 1
Yield of ethanol based on ethylene D ð 100 D 94.4 per cent
5.51
As 1 mol of ethanol is produced per mol of ethylene the stoichiometric factor is 1.

0.15 ð 2
Yield of ether based on ethylene D ð 100 D 5.44 per cent
5.51
The stoichiometric factor is 2, as 2 mol of ethylene produce 1 mol of ether.
Note: the conversion of ethylene, to all products, is given by:
mols fed mols out 55 49.49
Conversion D D ð 100
mols fed 55
D 10 per cent

The yield based on water could also be calculated but is of no real interest as water
is relatively inexpensive compared with ethylene. Water is clearly fed to the reactor in
considerable excess.

Example 2.12
In the chlorination of ethylene to produce dichloroethane (DCE), the conversion of
ethylene is reported as 99.0 per cent. If 94 mol of DCE are produced per 100 mol of
ethylene fed, calculate the overall yield and the reactor (reaction) yield based on ethylene.
The unreacted ethylene is not recovered.